在Visual Studio 2010的服务器资源管理器中无法连接到Sql Server,对话框提示"找不到请求的.NET Framework Data Provider。可能没有安装"
解决办法:
打开C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CONFIG\machine.config,复制DbProviderFactories节点下的内容到C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\Config\machine.config中的相应位置(原内容为空).
<DbProviderFactories>
<add name="Odbc Data Provider" invariant="System.Data.Odbc" description=".Net Framework Data Provider for Odbc" type="System.Data.Odbc.OdbcFactory, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
<add name="OleDb Data Provider" invariant="System.Data.OleDb" description=".Net Framework Data Provider for OleDb" type="System.Data.OleDb.OleDbFactory, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
<add name="OracleClient Data Provider" invariant="System.Data.OracleClient" description=".Net Framework Data Provider for Oracle" type="System.Data.OracleClient.OracleClientFactory, System.Data.OracleClient, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
<add name="SqlClient Data Provider" invariant="System.Data.SqlClient" description=".Net Framework Data Provider for SqlServer" type="System.Data.SqlClient.SqlClientFactory, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
</DbProviderFactories>
来源：https://www.cnblogs.com/hlizard/archive/2011/10/04/2199169.html